"Yesterday afternoon, I was made aware, for the first time, of allegations of improper conduct by my chief of staff while under the employment of my office," Rubio said in a statement.

"By early this afternoon, I had sufficient evidence to conclude that while employed by this office, my chief of staff had violated office policies regarding proper relations between a supervisor and their subordinates."

Rubio said he traveled from Florida to Washington, D.C., and "terminated his employment effective immediately."

"We have taken steps to ensure that those impacted by this conduct have access to any services they may require now or in the future," he said in the statement.

"Pursuant to the wishes of those victimized by this conduct, we will not be disclosing any further details about the incidents which occurred."

Rubio added he will be formally notifying the appropriate congressional administrative offices on Monday morning.